Update computeArraySize() to use ComputeMultiple() to determine the array size associated with a malloc; also extend PerformHeapAllocSRoA() to check if the optimized malloc's arg had its highest bit set, so that it is safe for ComputeMultiple() to look through sext instructions while determining the optimized malloc's array size

llvm-svn: 86676

1 files changed, 7 insertions, 7 deletions

diff --git a/llvm/lib/Transforms/IPO/GlobalOpt.cpp b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
index 4013272cd27..442f2fb6552 100644
--- a/llvm/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
@@ -1321,15 +1321,15 @@ static GlobalVariable *PerformHeapAllocSRoA(GlobalVariable *GV, CallInst *CI,
   //      if (F1) { free(F1); F1 = 0; }
   //      if (F2) { free(F2); F2 = 0; }
   //    }
-  Value *RunningOr = 0;
+  // The malloc can also fail if its argument is too large.
+  Constant *ConstantZero = ConstantInt::get(CI->getOperand(1)->getType(), 0);
+  Value *RunningOr = new ICmpInst(CI, ICmpInst::ICMP_SLT, CI->getOperand(1),
+                                  ConstantZero, "isneg");
   for (unsigned i = 0, e = FieldMallocs.size(); i != e; ++i) {
     Value *Cond = new ICmpInst(CI, ICmpInst::ICMP_EQ, FieldMallocs[i],
                              Constant::getNullValue(FieldMallocs[i]->getType()),
                                "isnull");
-    if (!RunningOr)
-      RunningOr = Cond;   // First seteq
-    else
-      RunningOr = BinaryOperator::CreateOr(RunningOr, Cond, "tmp", CI);
+    RunningOr = BinaryOperator::CreateOr(RunningOr, Cond, "tmp", CI);
   }
 
   // Split the basic block at the old malloc.
@@ -1490,7 +1490,7 @@ static bool TryToOptimizeStoreOfMallocToGlobal(GlobalVariable *GV,
   // This eliminates dynamic allocation, avoids an indirection accessing the
   // data, and exposes the resultant global to further GlobalOpt.
   // We cannot optimize the malloc if we cannot determine malloc array size.
-  if (Value *NElems = getMallocArraySize(CI, TD)) {
+  if (Value *NElems = getMallocArraySize(CI, TD, true)) {
     if (ConstantInt *NElements = dyn_cast<ConstantInt>(NElems))
       // Restrict this transformation to only working on small allocations
       // (2048 bytes currently), as we don't want to introduce a 16M global or
@@ -1535,7 +1535,7 @@ static bool TryToOptimizeStoreOfMallocToGlobal(GlobalVariable *GV,
                extractMallocCallFromBitCast(Malloc) : cast<CallInst>(Malloc);
         }
       
-        GVI = PerformHeapAllocSRoA(GV, CI, getMallocArraySize(CI, TD), TD);
+        GVI = PerformHeapAllocSRoA(GV, CI, getMallocArraySize(CI, TD, true),TD);
         return true;
       }
     }